<script>
    var fd = new FormData();
    fd.append('username', '性格');
    fd.append('password', 'qweqweqwe');
    const xhr = new XMLHttpRequest();
    xhr.open('post', 'http://www.liulongbin.top:3006/api/formdata');
    xhr.send(fd);
    xhr.onreadystatechange = function () {
        if (xhr.readyState == 4) {
            console.log(xhr.responseText);
        }
    }
</script>